Spark plug



Nov. 8, 1938. RABEZZANA 2,135,624

SPARK PLUG Filed June 1, 1957 2 sheets-sneu 1 NOV 8', 1938. H. RABEzzAA SPARK PLUG Filed June l, 1937 2 Sheets-Sheet 2 Patented Nov. 8, 1938 SPARK PLUG Hector Babemna, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application June 1, 1937, serial No. 145,662

Claims.

My invention relates to spark plugs and the object thereof is to provide an improved single piece plug, wherein the parts which comprise the same are permanently secured together and pro- 5 vide a unitary structure, which is simpler in construction than has heretofore been the case in l5 free access to a considerable part of the peripheral surface thereof.

'I'he drawings accompanying and forming a part of this specification illustrate various embodiments of my invention, and the features wherein the same consists are particularly pointed out and claimed in the concluding claims.

In the drawings: e

Figure v1 is a view showing the metal parts in section, and the insulating member of my improved spark plug in side elevation.

Figure 2 is a view showing the entire plug in side elevation, so that a better understanding may be had as to how the external atmosphere has direct access to the central part of the insulating member.

Figure 3 is a view showing a-section upon a transverse plane indicated by the line 3 3, Figure 1.

Figure 4 is a view showing a half sectlon'and half elevation of a modined form of my invention. I

Flgln'eisaviewshowingasectionupona transverse plane indicated by the line 5 5, Figure 4. Figure 6 -is a view showing a half section and half elevation of a spark plug similar to the one shown in Figures 1 and 2, but wherein the an-'f nular holding member thereof is modined.'

Figures I and 8 are sectional and fragmentary Aviews showinganother form of my invention.

Figure 9 is a view showing the metal parts in section and the insulating member in side elevatin, of a mpdifled i'orm of my invention.

Figure 10 is a view showing a section upon a transverse plane indicated by the line II-II,

Figure 9.

Referring now to the drawings, the numeral Il designates an annular base member the lower or inner end of which is threaded to screw into an opening in the cylinder of an internal combustion engine, and the upper or outer end of which has a flange I2; and the numeral I3 designates the insulating member of the plug which is commonly made of porcelain or similar ceramic material, and the lower end of which extends into the 5 threaded part of the base as shown. 'I'he in sulated member has a passage extending longitudinally through it for the central electrode, the lower end I4 of which is disposed adjacent the grounded electrode I5 as is usual in spark 10 plugs. The base member'is substantially the same in each of the forms of my invention illustrated. as is also the insulating member I3, a1- though the enlarged central part thereof is somewhat shorter in ,Figures 4, 6, 7 and 9 than in 15 Figures 1 and 2.`y

'I'he central part of the insulating member is enlarged as at I6, as is usual in spark plugs, and a lower annular shoulder thereof rests upon the flange I2 whereby the insulating member is sup- 20 ported from the base. As is also usual in spark plugs the base or iiange is shown as provided with a narrow annular ridge I1 for securing a. more perfect gas tight joint as the parts of the plug are assembled under pressure as will hereinafter 25 appear.

The numeral I8, Figures 1 and 2, designates an Iannular substantially cylindrical holding member which surrounds the upper part of the insulating member, and has an inwardly extending 30 flange I9 at its upper end. 'I'he insulating member has an upper annular shoulder 20; and 2i is an annular metallic member c-shaped in cross section and which is made of resilient material, this member being interposed between the ange 35 I8 and the shoulder 20. In assembling the parts pressure is applied to the upper end of the holding member I8 (the base member I I being supported upon the anvil of a suitable press) whereupon the resilient washer or gasket member 2| is 40 distorted by compression and acts as a strong and stiff spring to force the insulating member against the base throughout the life of the plug. 'I'he holding member is shown as having 'a series of depending lugs 22 which contact with the 45 periphery of the annular flange I2, and the lower ends of these lugs are welded, brazed or otherwise fastened to said flange whilepressure is Vmaintained between the holding member and the base and the annular member 2| is held under com- 50 pression, whereby the parts of the plug are held in a permanently assembled condition with the member 2| under stress during the life of the plug.

Figures 4 and 5 show a form of my invention 56 wherein the annular holding member and the resilient member or gasket which acts to force the .insulating member against the base are made integral with one another, as distinguished from as separate elements as in Figures l and 2; said member being made for example from spring steel at stock and having an inwardly curved part or ring 23 which is C-shaped in cross section which is pressed against the annular shoulder 20 of the insulating member when the parts are assembled under pressure, as aforesaid, the annular holding member of which the G-shaped ring 23 is a part having also a series of depending lugs 2l, the lower ends of which are secured, preferably by welding or brazing, to the annular flange i2 before the pressure whereby the part 23 is compressed so as to set up stress therein is relieved, thus and as in the form of my invention first described holding the parts of the plug together and providing a unitary spark plug.

It will be seen that in both the forms of my invention thus f ar described the lugs 22 and 24 are l spaced quite widely apart so that the surrounding atmosphere has comparatively free access to the insulating member of the plug, which results in that the insulating member is kept cooler than Would be the case if the openings or recesses between the lugs were not present.

Figure 6, however, shows a form of my invention wherein such openings are not present. In this form the cylindrical holding member 25 extends to the ange l2 and iits about the periphery thereof, and is fastened thereto while the parts of the plug are held together under compression, the saine as in all the forms of my invention herein described. The holding member 25 while it has no openings between depending lugs is commonly slitted up from the lower end thereof to insure better contact with the iiange i2 during welding of the parts together, as indicated by the reference numeral 26.

Figures 'l and 8 illustrate a form of my invention wherein the annular holding member is in the form of an upper narrow ange 2l having depending lugs 28 integral therewith and the lower ends or which are welded or brazed te the flange i2 of the annular base il; and wherein the annular resilient C-shaped member 2B approaches more nearly a torus than does the equivalent member 2l in Figures l, 6 and 9. This member 29 is held under compression in the iinished plug between the ange 21 and the annular shoulder 3i) of the insulating member the same as in the other forms of my invention herein described.

Figures 9 and 10 illustrate a form of my invention wherein the member 3l which holds the parts of theplug together and in permanently assembled relation is of conical rather than cylindrical form, and wherein the lugs 32 have hook-like extremities which enter a groove 33 in the flange i2 as the parts are assembled. The part 3l has a flange 34 at its upper end which holds a c-shaped resilient member 35 made, for example, of spring steel, between itself and an annular shoulder 36 upon the insulating member I3; and during the assembling of the parts the holding member 3i with its lugs @i2 partially bent inward is pressed toward the base il, thus subjecting the C-shaped member 35 to compression and producing a permanent distortion thereof and stress therein and, while the parts are held under compression, the hook-shaped extremities of the lugs 32 are forced inward and into the groove 33. Engagement between these parts will in many cases form a satisfactory method or holding the parts together although the lower ends of the lugs may be brazed 'or welded in place in the groove, thus forming a stronger and more secure connection between the annular holding member and the base o! the plug.

Having thus described and explained myA invention I claim and desire to secure by Letters Patent:

l. In a spark plug, an annular base having an inner externally threaded part, and an annular liange at its outer end; an insulating member supported by said base and extending into said threaded part, and having an annular shoulder; an annular holding member surrounding said insulating member and having depending lugs which are fastened to said annular ange, to thereby hold said insulating member permanently assembled with said base; an annular metallic and resilient member arranged between said holding member and said shoulder; a central electrode extending through a passage in said insulating member; and a grounded electrode at the inner extremity of said threaded portion.

2. In a spark plug, an annular base having an inner externally threaded part, and an annular flange at its outer end; an insulating member supported by said flange and extending into said threaded part, and having an annular shoulder spaced apart from said flange; an annular holding member surrounding said insulating member and extending above said shoulder and having an inwardly extending flange at its upper end, and which holding member has depending lugs which are welded to said annular flange to thereby hold said insulating member permanently as sembled withl said base; an annular metallic and resilient member arranged between the ilange at the 'upper end of said holding member and said shoulder; a central electrode extending through a passage in said insulating member; and a grounded electrode at the inner extremity of said threaded portion.

3. In a spark plug, an annular base having an inner externally threaded part, and an annular flange at its outer end; an insulating member supported by said ilange and extending into said threaded part, and having an annular shoulder spaced apart from said flange; an annular holding member cylindrical in form surrounding said insulating member and extending above said shoulder and having an inwardly extending ange at its upper end, and the lower end oi' which holding member is fastened to the periphery of said annular flange to thereby hold said insulating member permanently assembled with said base; an annular metallic and resilient member C-shaped in cross-section arranged between 'the flange at the upper end of said holding member and. said shoulder; a central electrode extending through a passage in said insulatin member; and a grounded electrode at the inner extremity of said threaded portion.

4. In a spark plug, an annular base having an inner externally threaded part, and an annular ilange at its outer end; an insulating member supported by said flange and extending into said threaded part, and having an annular shoulder spaced apart from said flange; an annular holding member cylindrical in form surrounding said insulating member and extending above said shoulder and having an inwardly extending ange at its upper end, and which holding member has depending lugs the lower ends of which are welded to the periphery or said annular flange to thereby hold said insulating member permanently assembled with said base; an annular metallic and resilient member C-shaped in cross-section arranged between the flange at the upper end of said holding member and said shoulder; a central electrode extending through a passage in said insulating member; and a grounded electrode at' the inner extremity of said threaded portion.

5. n a spark plug, an annular base having an inner externally threaded part, and an annular ange at its outer end; an insulating member supported by said annular ange and extending into said threaded part and having an annular shoulder; an annular holding member separate from said base surrounding said insulating member and having an inwardly curved upper end which is c-shaped in cross-section, and resilient, and which inwardly curved upper end overlies the shoulder aforesaid, the lower end of said holding member being welded to the periphery oi? said annular iiange to thereby hold said insulating member permanently assembled with said base; a central electrode extending through a passage in said insulating member; and a grounded electrode at the inner extremity of said threaded portion.`

HECTOR RA'BEZZANA. 

